1. Field of the Invention
The invention relates to a charged particle system, such as a lithography system.
2. Brief Description of Related Art
Lithographic processes are commonly used in the manufacture of semiconductor elements, such as integrated circuits (ICs), LSIs, liquid crystal elements, micro-patterned members and micromechanical components.
A charged particle lithography system generally comprises a beam generating system with a charged particle source, a patterning device and a particle-optical projection system. One or more charged particle beams generated by the beam generating system are generally directed to be incident on the patterning device adapted to endow the incident beam with a pattern or, in other words, generate a pattern of charged particle beamlets. The pattern is conveyed by charged particle beamlets transmitted through the patterning device which are subsequently focused and imaged, usually at a reduced scale, by the particle-optical projection system onto a substrate comprising a layer that is sensitive to charged particles such that the pattern defined by the patterning device is written onto the substrate.
The trend towards ever more sophisticated semiconductor devices requires semiconductor elements of smaller size and higher complexity which, in turn, places higher demands on performance and throughput achievable with lithography systems.
In lithographic processes, the substrate usually comprises a large number of dies, i.e. individual sections of the substrate onto which a predetermined device structure is to be written by exposure to patterned charged particle beams. Since a cross-section of the predetermined device structure is generally larger than a cross-section of the patterned beam, writing each device structure requires multiple exposure steps, which are generally performed by scanning the substrate relative to the projection system such that lines of each device structure are sequentially written onto the respective die. This type of exposure requires exact alignment of adjacent lines in order to avoid discontinuities or other faults in the written device structures.
Similar problems arise in charged particle inspection systems, wherein the projection system provides for illumination of a substrate to be inspected and/or is configured to provide a good image of the inspected region of the substrate surface onto a detector.
Therefore, it is an object of the present invention to provide an improved charged particle system.